“By following the path of [Qadhafi] and deploying military forces to crush peaceful demonstrations, al-Assad and those loyal to him have lost the legitimacy to remain in power in Syria,” the senators said. “We urge President Obama to state unequivocally — as he did in the case of Qadhafi and [Egyptian President Hosni] Mubarak — that it is time for Assad to go.”

On Wednesday Arizona Sen. Jon Kyl, the chamber’s No. 2 Republican, criticized Obama’s response to the unrest in Syria and called for sanctions and the withdrawal of the U.S. ambassador.

More than 450 people have been killed by Syrian security forces amid weeks of anti-government demonstrations, according to The Associated Press.

Obama, the senators said Thursday, should pursue sanctions and other “tangible diplomatic and economic measures” to pressure leaders of the al-Assad regime to stop the crackdown.

“Bashar al-Assad has been given countless chances to pursue meaningful dialogue and reform. He has squandered all of them,” the senators said.

“Rather than hedging our bets or making excuses for the Assad regime, it is time for the United States, together with our allies in Europe and around the world, to align ourselves unequivocally with the Syrian people in their peaceful demand for a democratic government.”

Lieberman is chairman of the Senate Homeland Security Committee and Governmental Affairs, while McCain is the top Republican on the Senate Armed Services Committee, a panel on which Graham also serves.